A new series of natural cephalosporins have recently been reported and given the class name of cephamycin. The distinguishing feature of this class of cephalosporins is the 7.alpha.-methoxy group. Two naturally-occurring cephamycins have been reported by Nagarajan et al., J. Amer. Chem. Soc., 93, 2308 (1971). These compounds have the cephalosporin C acyl group at position 7 and acetoxymethyl or carbamoyloxymethyl at position 3. These compounds and others which have been modified at position 3 are disclosed in Belgian Patent No. 764,160 (Farmdoc 61445S) and Netherlands Patent No. 7103135 (Farmdoc 62434S).
Compounds with other acyl groups have been disclosed. For example, 7-methoxycephalothin is reported in Netherlands Patent No. 7304755 (Farmdoc 66543U) and J. Amer. Chem. Soc., 94, 1408 (1972). The same patent also discloses 7.alpha.-methoxy-7.beta.-thienylacetamido-3-carbamoyloxy-3-cephem-4-carbox ylic acid. South African Patent No. 71,3229 discloses compounds and process for preparing them with various acyl groups.